Dumb Question re: resolution off 15 pin

Trying to google but can't find a good answer

I want to buy a laptop. 95% of the time i'll be using my 20" LCD not the laptop screen

the laptop i have chosen only has a 15pin VGA out connector.

What resolution will I be limited to? Currently 1400 x 1050.

No limit, just your graphics card / monitor limits

i managed over 2500x2000 on a crt screen a while back (22" philips).

Schweet! Just cos I'm currently running DVI and didn't want to downgrade